Hypodermic syringes are conventionally provided with a sheath for enclosing the needle to protect it against contamination and breakage during handling. Hypodermic syringes are used heavily by health workers and others for purposes of injecting medication into a person. This process requires filling of the syringe with the medication and thereafter emptying all or part of the contents during an injection procedure. During filling and emptying of the syringe, it is necessary to remove the sheath and replace it. It is during replacing of the sheath, which quite often takes place under hurried and stressful situations, that the health worker will puncture his or her fingers. This is not a serious problem when the needle has not been used, as it is then sterile, but it can be a deadly problem when the needle has been used on a person having a communicable or transmittable disease, as that disease then can be transmitted to the worker using the syringe. For example, it has been known for some workers to have contracted AIDS from such a needle puncture.
Heretofore, there have been a number of proposed sheath constructions directed at solving this problem. For example, funnel-shaped guides have been provided at the inlet end of a sheath. Some sheaths have been constructed so that they can be mounted on a syringe laterally, but they then require secondary sheaths to completely enclose the needle. There also have been some sheaths with relatively small shields attached or formed integrally with the sheath and which function to provide minimal protection against needle punctures. The problem encountered with attempting to provide large shields to better protect against puncture lies in the difficulties encountered in shipping and storing the syringes because they require a great deal of space.
Because of the increasing problems confronting health workers who treat patients with highly communicable diseases and the chance of enduring a needle puncture, it is imperative that a solution be found to protect the health workers.